Brnabić holds an MBA diploma of the University of Hull and worked for over a decade with international organizations, foreign investors, local self-government units, and the public sector in Serbia.

Prior to Brnabić's appointment to the Government of Serbia, she was director of Continental Wind Serbia[8], where she worked on the implementation of the investment of €300 million into a windpark in Kovin[9]. She was a member of the managing board of the non-profit foundation Peksim[10].

She has been engaged in different US consulting companies that implemented USAID-financed projects in Serbia. She was deputy manager of the Serbia's Competitiveness Project, the expert on the Local self-government Reform Program in Serbia and the senior coordinator of the Program of Economic Development of Municipalities.[citation needed] She actively participated in the foundation of the National Alliance for Local Economic Development (NALED) in 2006.

She made great efforts to build capacities of NALED for representation of interests of the business sector, local self-government units and the civil society in Serbia. During that engagement, she participated in the introduction of the concept of local economic development in Serbia and building of potentials of municipalities to improve the business environment at the local level with active promotion of investments. She became a member, and thereafter the President of the Managing Board of NALED.

In an interview on November 14, 2018 with the German public broadcaster Deutsche Welle, Brnabić denied that the July 1995 massacres of Bosniaks by Bosnian Serb forces in Srebrenica had been an act of genocide.[22] Two weeks later, the European Parliament adopted a resolution saying that the parliament regretted the continuing denial of the Srebrenica genocide by parts of the Serbian authorities and recalled that full cooperation with the ICTY and its successor mechanism included accepting its judgements.[23]

In December 2018, Commenting on the announced transformation of the Kosovo Security Force into the Kosovo Armed Forces, Brnabić said: “I hope we won’t have to use our military, but at the moment, that’s one of the options on the table because one cannot witness a new ethnic cleansing of the Serbs and new Storms - although Edi Rama is calling for them. When someone knows you have a strong army, then they have to sit down and talk to you”.[24][25]